Use the friendly ID gem for contest slugs

db/migrate/20250326162646_remove_slug_from_contests.rb

@@ -0,0 +1,5 @@
+class RemoveSlugFromContests < ActiveRecord::Migration[8.0]
+  def change
+    remove_column :contests, :slug, :string
+  end
+end

db/migrate/20250326162828_add_slug_to_contests.rb

@@ -0,0 +1,6 @@
+class AddSlugToContests < ActiveRecord::Migration[8.0]
+  def change
+    add_column :contests, :slug, :string
+    add_index :contests, :slug, unique: true
+  end
+end

db/migrate/20250326162920_create_friendly_id_slugs.rb

@@ -0,0 +1,21 @@
+MIGRATION_CLASS =
+  if ActiveRecord::VERSION::MAJOR >= 5
+    ActiveRecord::Migration["#{ActiveRecord::VERSION::MAJOR}.#{ActiveRecord::VERSION::MINOR}"]
+  else
+    ActiveRecord::Migration
+  end
+
+class CreateFriendlyIdSlugs < MIGRATION_CLASS
+  def change
+    create_table :friendly_id_slugs do |t|
+      t.string :slug, null: false
+      t.integer :sluggable_id, null: false
+      t.string :sluggable_type, limit: 50
+      t.string :scope
+      t.datetime :created_at
+    end
+    add_index :friendly_id_slugs, [ :sluggable_type, :sluggable_id ]
+    add_index :friendly_id_slugs, [ :slug, :sluggable_type ], length: { slug: 140, sluggable_type: 50 }
+    add_index :friendly_id_slugs, [ :slug, :sluggable_type, :scope ], length: { slug: 70, sluggable_type: 50, scope: 70 }, unique: true
+  end
+end